Got kids? You’re more likely to have low testosterone

A new longitudinal study shows that men with lots of testosterone are more …

In the animal kingdom, it’s no secret that the most masculine male usually gets the girl; big bodies, large antlers, and low frequency calls tend to drive the ladies wild. But once the guy gets the girl and the girl gets pregnant, high levels of testosterone aren’t necessarily a good thing. According to new research in PNAS, males with high testosterone are more likely to become fathers, but once they have children, their testosterone levels fall dramatically.

In animals like birds where paternal care is common, males tend to downregulate their testosterone production once babies are born. Humans, however, are one of the few mammalian species in which males help raise the offspring. Since this is a rare trait among mammals, we don’t know much about our reproductive strategies when it comes to testosterone.

This longitudinal study used data from a long-term dataset of males living in Cebu City in the Philippines. The researchers measured morning and evening salivary testosterone levels in 642 21-year old males. Then, when the guys were 26, these measurements were taken again; by that time, many were married and had children.

Not surprisingly, men with higher testosterone levels at 21 years of age were more likely to be married and have children five years later.

It's very common for men to undergo age-related decreases in testosterone, and most of the men in the study did have slightly lower testosterone levels by the time they were 26. However, men who had children by the time the second measurement was taken had much greater decreases than those that were still single and those that had gotten married but not had children.

Dads with newborns were most strongly affected; new fathers whose kids were less than a month old had the largest drops in testosterone production, when compared to their baseline. These hormone changes weren’t accounted for by their sleep quality, stress levels, or time budgeting.

Fathers that were more involved in child care and spent more time with their children had lower testosterone levels than those that didn’t spend much time caring for their kids and those that were completely uninvolved with their children. Furthermore, the baseline testosterone measurement taken at 21 years of age was completely unrelated to how invested the fathers were in their children’s care five years later. Taken together, this strongly suggests that caring for his kids can actually suppress a father’s testosterone production.

While testosterone may help attract females, it can be detrimental to a relationship’s stability. In previous research, men with high testosterone levels were more likely to have marital problems, and less likely to feel empathy when an infant cries. It’s likely that the down-regulation of testosterone production seen here is an evolutionary adaptation to increase reproductive success. A lot of testosterone may help get the girl, but a little less of it may help raise the family.

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Kate is a science writer for Ars Technica. She recently earned a dual Ph.D. in Zoology and Ecology, Evolutionary Biology and Behavior from Michigan State University, studying the social behavior of wild spotted hyenas. Emailkate.shaw@arstechnica.com//Twitter@KateYoshida

These hormone changes weren’t accounted for by their sleep quality, stress levels, or time budgeting.

I'd be interested to see how they controlled for that.

"For our control sample, we took a group of men at random, and wired their houses with a siren that would go off at intervals ranging from 1-4 hours. To disable the siren, the men had to get up, make a glass of milk, pour it on the siren, and then dry it off. This was continued for a full month. We would also make sure to randomly call the men away from their work, and randomly yell at them as well. This involved picking something that was in no way their fault, and which they had no way of correcting."

These hormone changes weren’t accounted for by their sleep quality, stress levels, or time budgeting.

I would be curious how they determined that. e.g. They note right before this, "Dads with newborns were most strongly affected; new fathers whose kids were less than a month old had the largest drops in testosterone production, when compared to their baseline." I have 4 children and the periods of my life with the some of the worst sleep quality, highest stress levels, and the most difficult time budgeting were times right after their births. I am not sure how they could easily compare or eliminate the affect of these stresses in relation to other stresses.

Testicles must emit a sound only babies and toddlers can perceive, and it must subconsciously enrage them.

LOL Damn right..

On a serious note, WTH of a stupid study. My wife and I have three sons, the twins were born in January.. In March I had a physical and my blood chemistry was all over the place according to my doctor. And he said "well no shit your not sleeping enough your body is all out of whack"...

My three nieces really love me for some reason (aged 6, 5 and 2) ever since they were 4, 3 and a baby. I really enjoy spending time with them. However, my wife and I are trying to get pregnant without success. I am getting all the usual tests done now, but I wonder if there is a link?

These hormone changes weren’t accounted for by their sleep quality, stress levels, or time budgeting.

I'd be interested to see how they controlled for that.

Agreed. I can't imagine there's many situations where people without kids get this level of tired. Even people I know who did shift work or emergency services got more sleep before kids. I've reached levels of tired now that even my all-nighter-who-needs-sleep university self would have balked at.

As a new father (entering the third week), this study is pretty on the nose. Decreases in testosterone scale inversely to production of oxytocin (the so-called "love hormone"), which *does* appear to serve the purposes of nurturing an emotional connection while increasing patience with that child's inevitable screeching and demands. Mercifully our daughter's been quiet and cheerful.

Other variables to investigate: does testosterone decrease more with difficult or colic-stricken babies? Does regular exercise lessen the change in testosterone? (I suspect the latter is at least somewhat true.)

So, a woman is attracted to a manly man, has a kid with him, he gets all soft (figuratively and literally, since lower test can promote weight gain, esp. if dietary habits aren't changed), and then she complains about him not being the man she used to love. Do you think this leads to some divorces? Where the woman expects the guy to remain the macho guy she fell in love, even after the kids are born?

So, a woman is attracted to a manly man, has a kid with him, he gets all soft (figuratively and literally, since lower test can promote weight gain, esp. if dietary habits aren't changed), and then she complains about him not being the man she used to love. Do you think this leads to some divorces? Where the woman expects the guy to remain the macho guy she fell in love, even after the kids are born?

But if he does remain the macho guy she fell in love with, she complains about him being too macho.

As the dude in the picture, I just wanted to allay the concerns of everyone who was worried that the encapsulated tender moment with my daughter would end in a fury of WTFOMGBBQ sauce-fueled cannibalism (I'dve thought the OMGWTFBBQ Eye Lazers uhv DEATH were more of a concern, but that must just be my low testosterone speaking)... She's currently 2 1/2 years old and in perfect health, though she's always <a href='http://www.flickr.com/photos/lucidialohman/6098274546/'>on the lookout for cannibalistic daddies</a>.

Never thought a photo would actually be plucked from Lulu's photostream via the Creative Commons route, but I guess I can take solace that its use doesn't denegrate or suggest anything about any of the subjects of the pho.... D'OH! Creative Commons FAIL :-)

They're missing an important point with this study. They imply that those males who have more of a nurturing role are more likely to have low T. They did not consider if low T (and thus a relative increase in estrogens:T ratio) CAUSED nurturing behaviors. I think this is a very important distinction.

As the dude in the picture, I just wanted to allay the concerns of everyone who was worried that the encapsulated tender moment with my daughter would end in a fury of WTFOMGBBQ sauce-fueled cannibalism (I'dve thought the OMGWTFBBQ Eye Lazers uhv DEATH were more of a concern, but that must just be my low testosterone speaking)... She's currently 2 1/2 years old and in perfect health, though she's always <a href='http://www.flickr.com/photos/lucidialohman/6098274546/'>on the lookout for cannibalistic daddies</a>.

Never thought a photo would actually be plucked from Lulu's photostream via the Creative Commons route, but I guess I can take solace that its use doesn't denegrate or suggest anything about any of the subjects of the pho.... D'OH! Creative Commons FAIL :-)

It's the red eyes that make the picture creepy. You should do something about it for your future pictures (either at the camera level, or at post).

These hormone changes weren’t accounted for by their sleep quality, stress levels, or time budgeting.

I'd be interested to see how they controlled for that.

Agreed. I can't imagine there's many situations where people without kids get this level of tired. Even people I know who did shift work or emergency services got more sleep before kids. I've reached levels of tired now that even my all-nighter-who-needs-sleep university self would have balked at.

It's easier to control for in the Philippines than it would be in the US or even worse, northern Europe.

In the lower social classes, taking care of a crying baby is a woman's job. That's mom's, grandma's, auntie or older sister's job. Mom, grandma and baby will sleep in a separate room from the head of the household. In the upper middle classes, crying baby is the domestic/nanny's job. Nanny's room is often attached to the nursery.

I know recent fathers from the affluent Asian countries such as Japan or Korea that have almost never changed their kids diapers or fed them in the middle of the night. I bet a large proportion of fathers in SE Asia would find the entire concept entirely foreign to them.

It'd be interesting to know how much of this is related to the actual proximity of the kids. Is there a measurable testosterone drop in recent fathers who for whatever reason can't be close to their newborn children? Overseas workers, military, prison, etc.

And as the person who made that baby and took that pic, I'd like to state for the record that my husband's nuts are in perfect working order and that I never allow him near the BBQ sauce. (He's also currently in therapy for his retina condition.)

We're only talking about a relatively small variation in testosterone. Enough (if this study is born out) for a behavioral effect but it's going to have no effect on your appearance/sexual function/energy.

You're thinking all kinds of wrong if you see your serum testosterone as some kind of RPG stat of your manliness.

If you've turned into a fat fuck since having kids... that was going to happen anyway and the blame lies in your shitty genes or your lack of willpower.

As the dude in the picture, I just wanted to allay the concerns of everyone who was worried that the encapsulated tender moment with my daughter would end in a fury of WTFOMGBBQ sauce-fueled cannibalism (I'dve thought the OMGWTFBBQ Eye Lazers uhv DEATH were more of a concern, but that must just be my low testosterone speaking)... She's currently 2 1/2 years old and in perfect health, though she's always <a href='http://www.flickr.com/photos/lucidialohman/6098274546/'>on the lookout for cannibalistic daddies</a>.

Never thought a photo would actually be plucked from Lulu's photostream via the Creative Commons route, but I guess I can take solace that its use doesn't denegrate or suggest anything about any of the subjects of the pho.... D'OH! Creative Commons FAIL :-)

slightlyperfect wrote:

And as the person who made that baby and took that pic, I'd like to state for the record that my husband's nuts are in perfect working order and that I never allow him near the BBQ sauce. (He's also currently in therapy for his retina condition.)

Wow. Never thought my stupid caption would a) solicit actual responses from the photographer and the subject and b) cause them to register just to post!

The children aren't why they have Low-T. It's because after having children, the wives don't want sex anymore and the guys just spank-it with reckless abandon. ;)

Blaming the men's wives for their decreases in testosterone is ludicrous and insensitive. If you had been in labor for 24 hours or more, pushed an average of a 7 lb. baby through your birth canal, and after six weeks post-partum were still bleeding, you wouldn't have much of a sexual appetite. Throw in nipple soreness from nursing and sleep deprivation, and you might be able to understand why many new moms aren't interested in sex. What's more, obstetricians tell new moms who've delivered vaginally (as opposed to C-section) not to have sex for at least six weeks post-partum to prevent infection and so that they can heal.